Hot-gas reciprocating engine



Nov. 4, 1952 F. L. VAN WEENEN 6,

HOT-GAS RECIPROCATING ENGINE Filed April 12, 1950 I INVENTOR.

FRANCISCUS LAMBERTUS VAN%WEENEN BY AGENT Patented Nov. 4, 1952 HOT-GASRECIPROCATING ENGINE Franciscus Lambertus van Weenen, Eindhoven,Netherlands, assignor to Hartford National Bank and Trust Com trusteepany, Hartford, Conn., as

Application April 12, 1950, Serial No. 155,382 In the Netherlands May20, 1949 Claims.

This invention relates to hot-gas reciprocating engines comprising aregenerator and a cooler. The working medium of a hot-gas reciprocatingengine gives off heat in traversing the regenerator in one direction, sothat the temperature of the medium falls, and absorbs heat in traversingthe regenerator in the other direction so that the temperature of theworking medium rises, a comparatively great temperature gradientexisting across the regenerator. Thus, for instance, the hot end surfaceof the regenerator filling material may have a temperature of 600 C.,and the cold end surface 100 C.

The regenerator is contained in a space bounded by an outer wall whichis generally secured, to one or more parts of the engine at the line ofdemarcation of the cold end surface of the regenerator filling material.Owing to the great temperature difference across the regenerator fillingmaterial a comparatively great temperature difference also exists acrossthis wall. Thus, for example, the temperature of the wall at the heightof the hot end surface of the regenerator filling material mayapproximately be 600. C., and the temperature at the height of the coldend surface of the regenerator filling material is substantially thetemperature of the cooler.

As a rule, the optimum height of the regenerator filling material iscomparatively small, so that the temperature difference in the wall willprevail over a comparatively small height. However, the expansion of thewall at the end having a higher temperature materially exceeds theexpansion at the end having a lower temperature, which results inconsiderable strains in the material of the wall. Moreover, if the wallsurrounding the regenerator space is secured to the cooler, the leakageof heat to the cooler will be comparatively considerable owing to thesmall height of the wall.

The object of the present invention is to mitigate the aforesaiddisadvantages.

According to the invention, a hot-gas reciprocating engine comprising aregenerator and a cooler, is characterised in that the regenerator spaceis bounded by a substantially cylindrical outer wall which, viewed fromthe hot end surface of the regenerator filling material, extends pastand is secured to one or more parts of the engine beyond the cold endsurface of the regenerator filling material. The height of the wall overwhich the temperature gradient prevails thus exceeds that of theaforesaid known construction and hence the strains in the wall arereduced.

If the cooler adjoins the cold end surface of the regenerator, a simpleand compact construction may be obtained.

The distance by which the wall extends past the cold end surface of theregenerator filling material is preferably at least 0.3 times the heightof the regenerator filling material. The term height of the regeneratorfilling material is to be understood to mean the distance between thecold end surface and the hot end surface of the regenerator fillingmaterial.

In order to reduce the strains in and to ensure even expansion of theWall, the wall may be, viewed from the hot end surface of theregenerator filling material in the direction of the cold end surfacethereof, of decreasing thickness.

I Since the regenerator filling material should have a substantiallyuniform cross section throughout its height, it is of importance thatthe outer surface of the regenerator and, consequently, the inner sideof the wall should be substantially cylindrical in the working state ofthe engine. This is ensured by providing that the inner side of the Wallis conical in the cold state, the greater expansion at the upper side ofthe skirt now being reduced by the. greater wall thickness in situ.

As a rule, the wall will merge into another wall of materially greaterthickness both at its end adjacent the hot and at its end adjacent thecold end surface of the regenerator filling material. To prevent thewall at the point where it merges into another wall of materiallygreater thickness from becoming too rigid, it is advisable that at thepoint where the wall merges into another annular wall at right angles tothe axis of the wall, a slot should be provided in the other wall.

The latter may, for example, be a flange by means of which the wall issecured to one or more parts of the engine, or it may be another wallbounding one of the end surfaces of the regenerator space.

In order to reduce the leakage of heat through the wall to the cooler,the part of the wall which extends past the cold end surface of theregenerator filling material, surrounds the cooler substantiallythroughout that part of its length with a little clearance.

Since the height of the regenerator wall between the hot end surface ofthe regenerator filling material and the point of attachment to thecooler materially exceeds that of the con- .forming the 'interstice I9.

I structions hitherto known, the leakage of heat through the wall ismaterially smaller than in the known constructions.

In order that the invention may be more clearly understood and readilycarried into effect it will now be described more fully with referenceto the accompanying diagrammatic drawing, given by way of example,showing one embodiment thereof.

Fig. 1 shows part of a hot-gas reciprocating engine according to theinvention, and

Fig. 2 is a view of part of Fig. l on a larger scale.

In Fig. 1, the volume of the hot space I is determined by a displacer 2.Working medium flows between the hot space I and cold space 6 through aheater 3, a regenerator 4 and a cooler 5. The volume of the cold space 6is determined by the displacer 2 and a working piston I. By means of arod mechanism, both the displacer 2 andthepiston I are connected to acrank shaft (not shown) so that they reciprocate with.

aconstant phase ,diiference with reference to oneanother. Thermal energyis suppliedfrom a burner 9 to the heater which consists of hairpinshaped pipes arranged around the combustion chamber 8.

.The products of combustion leave the heater through an exhaust ID. Therequired combustion air is supplied to the burner through an annularduct II. The cooler is cooled by means of a cooling medium which issupplied and carried off through ducts I2.

The regenerator 4 is bounded by a cylindrical outer wall I3 likewisesurrounding the cooler, over, part of its height. The wall I3 is securedby meansof flanges I4-to the cooler and to the frame of the engine. Thewall I3 extends past the cold end surface of the regenerator fillingmaterial.

In Fig. 2 the cylindrical skirt is shown on a larger scale than in Fig.1 and the regenerator filling material is not shown. At the upper side,the wall I3 merges into another thicker wall It into which the pipes ofthe heater open, and at the bottom side the wall I3 merges into a flangeI4. The inner surface of the wall I3 is conical inthe cold state, sothat the thickness of the wall at the hot end of the regenerator fillingmaterial is greater than at the cold end thereof. To ensure asatisfactory expansion of the wall I3, the other wall I6 is furnishedwith a slot I! where it merges into the wall I3. Similarly, the flangeI4 has a slot I8 where it merges into the wall I3. The wall I3 surroundswith a little clearance the cooler substantially throughout the partextending past the cold end surface of the regenerator filling material,thus Since the distance between the hot end of the wall I3 and the areaof contact with the cooler is increased thereby, the leakageof heat tothe cooler will be considerably reduced.

vIt will be obvious that the construction according to the invention maybe applied in various hotgas engines.

What I claim is:

I. A hot gas engine comprising a first cylinder wall forming hot andcold spaces therein, means without said cylinder connecting said hot andcold spaces, said means including a regenerator and a cooler, saidregenerator comprising filler material having a hot end surface and acold end surface, said cooler being located adjacent said cold endsurface, a second cylindrical wall sur- 4 rounding said regenerator,extending past said cold end surface and surrounding part of the cooler,the end of that part of the wall surrounding said cooler being securedto said first cylindrical wall and that part of said wall surroundingsaidcooler being slightly spaced therefrom to form a clearancetherebetween to reduce the leakage of heat from said wall to the cooler.

2. A hot gas engine comprising a first cylinder wall forming hot andcold spaces therein, means Without said cylinder connecting said hot andcold. spaces, said means including a regenerator and a cooler, saidregenerator comprising a filler material having a hot end surface and acold end surface, said cooler being located adjacent said cold endsurface, a second cylindrical wall surrounding said regenerator,extending past said cold end surface at least a distance 0.3 times theheight of said filler material and surrounding part of the cooler, theend of that part of thewall surrounding said cooler being secured tosaid first cylindrical wall and that part of said wall surrounding saidcooler being slightlyspaced therefrom to form a clearance therebetweentoreduce the leakage of heat from said wall to the cooler.

3. A hot gas engine comprising a first cylinder wall forming hot andcold spaces therein, means without said cylinder connecting said hot andcold spaces, said means including a regenerator and a cooler, saidregenerator comprising a filler material having a hot end surface and acold end surface, said cooler being located adjacent said cold endsurface, a second cylindrical wall surrounding said regenerator havingan inner conical surface, said second wall extending past said cold endsurface and surrounding part of the cooler, the end of that part of thewall surrounding said cooler being-secured to said first cylindricalwall and that part of said wall surrounding said cooler being slightlyspaced therefrom to form a clearance therebetween to reduce the leakageof heat from said wall to the cooler.

4. A hot gas engine comprising a first cylinder wall-forming hot andcold spaces therein,- means without said-cylinder connecting said hotand cold spaces, said means including a regenerator and a cooler, saidregenerator comprising a filler material having a hot end surface and acold end surface, said cooler being located adjacent said cold endsurface, a second cylindrical Wall surrounding said regenerator having agradually diminishing thickness from its hottest to its coldest part,said second wall extending past said cold end surface and surroundingpart of the cooler, the end of that part of the wall surrounding saidcooler being secured to said first cylindrical wall and that part ofsaid wall surrounding said cooler being slightly spaced therefrom toform a clearance therebetween to reduce the leakage of heat from saidwall to the cooler.

5. A hot gas engine comprising a first cylinder wall forming hot andcold spaces therein, means without said cylinder connecting said hot andcold spaces, said means including a regenerator and a cooler, saidregenerator comprising a filler material having a hot end surface and acold end surface, said cooler being located adjacent said cold endsurface, a second cylindrical wall surrounding said regenerator,extending past said coldend surface and surrounding part of the cooler,said second cylindrical wall having an integral portion at each endthereof substantially at right angles to said second cylindrical wall,the end ofthat part of. the wall surroundleakage of heat from said wallto the cooler, and 5 said integral portions of said second cylindricalwall being provided with slots therein at the point of merger of saidsecond cylindrical wall and said integral portions thereof."

FRANCISCUS LAMBERTUS VAN WEENEN.

REFERENCES CITED llhe following references are of record in the file ofthis patent:

Number Number 6 UNITED STATES PATENTS Name Date Bair Sept. 4, 1888Wickstrom May 29, 1900 FOREIGN PATENTS Country Date Great Britain Dec.4, 1883 Great Britain July 12, 1920

